ALASKAN GLACIER STUDIES
wide in a north-south direction (PI. CLXXIV), and spreading eastward completely across the valley, a distance of over three and a half miles. By this expanded glacier bulb Copper River is forced over against the eastern wall of the valley, just as it is forced to the western wall immediately below by the ice bulb of Miles Glacier. Opposite the end of the expanded glacier the stream is narrowed (Baird Canyon) and the current quickened, although there are no txue rapids, and steamboats navigated this part of Copper River in 1909. The central part of the bulb is made up of clear ice and is lower than the eastern
FIG. 68. ALLEN GLACTEB AND ITS RELATIONSHIPS TO THE ADJACENT IGH TONGUES. (After D. C. Witherspoon, U. 8. Geol. Survey; the map first made in 1900 and republished with modifications in 1006.)
part, which is moraine-covered and clothed with vegetation. Copper River sweeps around the entire eastern and southern peripheries of the glacier, but on the northern side there is a large alluvial fan and a smaller one on the south side, separating the river and glacier. A rocky hill 600 feet high, rises out of the northern fan, and above it the river is broadened into a lake-like expanse.
Observations Previous to 1909. The Russians do not seem to have recognized this as a glacier, unless Grewingk also alludes to it as the "ice covered with earth," thought by us to refer to Miles Glacier. Abercrombie does not mention seeing the glacier in his 1884 exploration.